Prop / Combo Valve Test and/or Rebuild

[87_TX_T-Type]

So now that I have the engine all together, it's time to tackle the brakes that have been sitting for 8 years.

I tried flushing the system, but neither of the rear drums dripped a drop of fluid. After researching the prop/combo valve, I decided to pull mine to see if there was an obvious issue.

Prop_Valve

• 87_TX_T-Type
• May 31, 2017

While pulling it I finally started getting some brake fluid draining from the valve and the "T" on the front of the differential going to the rear drums.

I guess the valve itself looks fine, and I was able to squirt brake cleaner into each line port and have it come out another port. So there doesn't appear to any blockage. The tiny brass pin on the end has a little play in it, but doesn't move in or out. (Not sure any of this is good or bad.)

So a couple of questions:
1) Should I take the prop apart to inspect/test it further, or reinstall it and continue on to bleeding the master cylinder? Is there a way to test the prop valve for correct operation?
2) Somewhat unrelated, but I cannot remove the drum from one of the rear brakes. The pads are engaged even with the brake line off. (Could the e-brake be stuck?) Is there a trick to getting off a stuck drum, or do I just have to bang it off with a hammer?

Thanks!

 

[Chuck Leeper]

That valve has been involved in an update program by GM. The new one is brass.

 

[No disintegrations]

Can try and open all bleeders a generous amount. We called it gravity bleeding. Ones that drip nice can be shut. After 5 minutes or so you may get fluid from the dry ones. Or try a vacuum or injector tool.

 

[No disintegrations]

.

 

[NY Twin Turbo]

I'm not really sure how expensive the new ones are, but you have it off now. Just replace it. The brass ones are the GM issued replacements.

It's brakes. Don't mess around.

 

[baby6]

+1 for a good gravity bleed. That is what I would do if I were you

 

[markboss]

Change your rubber lines..New prop valve is about $40..Rock auto has both, cheap!

 

[87_TX_T-Type]

Thanks guys. I'm going to buy the brass valve. To the best of my knowledge the brakes were always the scariest part of this car growing up, so hopefully the brass unit is an upgrade.

Going to partially disassemble the master cylinder today to check for any issues. There are a LOT of posts on the subject, but let me know if there is any one thing I should watch out for consider how long the car sat.

Lastly... any suggestions on getting that rear drum off? I can't tell if it's an e-brake issue or just simply age. Banging it off with a hammer doesn't feel like the first course of action I should take.

Thanks again!

 

[turbo87adam]

You may have to back off the automatic shoe adjusters. You can probably YouTube the procedure on how to do that . It will be easier than explaining over the computer